SMC categorized its SMCWPCI-G2 EZ Connect™ g 802.11g 54Mbps Wireless PCI adapter drivers as "Old Product Download", so if you are trying to find from the current driver download page, using keyword "SMCWPCI", you will only find the nearest "SMCWPCI-G Driver" (notice the lack of digit '2' at the end).

There are three pdf and four driver zip files available for download under "SMCWPCI-G2" category. However without any descriptions for each driver file, you will have to download each one of them in order to check which is the correct driver for your system.

I have tried to download all drivers and examined them, below are the findings: